TPS61089: # TPS61089 SW-Pin and GND- Pin were shorted inside the IC

aida keiji

Part Number: TPS61089

A product using TPS61089 has returned as a defective product.
When I look for the cause,
SW-Pin and GND- Pin were shorted inside the IC.
What can be considered as the cause?

Best regards,

Keiji Aida

over 6 years ago

0 Helen chen over 6 years ago

TI__Mastermind 40080 points

Dear Sir,

What is your Vin, Vo and Io range?

0 aida keiji over 6 years ago in reply to Helen chen

Prodigy 70 points

Hi Helen,

The functional specifications are as follows.

Vin = 2.7~4.2V Li-po_Battey

Vout= 7.5V

Operating current=250mA~400mA

Inrush current= 3~4A 100uSec~300uSec

It is speculated that the internal FET or the parasitic diode is broken and shorted by some factor.

I think that is probably over current or over voltage.

Is this hypothesis possible?

I am concerned that the failure mode is short.

Best regards,

Keiji Aida

0 Helen chen over 6 years ago in reply to aida keiji

TI__Mastermind 40080 points

Hi Keji,

This part has current limit function. So over current will not cause damage. What about the layout and the schematic. Maybe this is an thermal issue.

And by the way, in what condition does the IC failed? During the 3-4A inrush current?

0 aida keiji over 6 years ago in reply to Helen chen

Prodigy 70 points

Hi Helen,

A broken IC will come back to me, and I can not confirm the situation.

The current limit is limited at 160 kΩ.

I was worried because the inrush current was flowing for a short period of time because it exceeded the specifications.

I think that there is no fever in this short time.

And it should be protected by thermal shutdown.

Best regards,

Keiji Aida

0 Helen chen over 6 years ago in reply to aida keiji

TI__Mastermind 40080 points

Dear Sir,

For the TPS61089, since it has current limit function, it will not be damaged if the load current is not big enough. It will be damaged only if the load current is very big.

Could you please send the related sch and the pcb layout to us? I need to check the layout file.

0 aida keiji over 6 years ago in reply to Helen chen

Prodigy 70 points

Hi Helen,

Thank you for continuing the review.

I will attach the data.

Maybe you can see it using ZUKEN's CR-5000 Viewer.

Best regards,

Keiji Aida

BB_Rev2.0.pcb

0 Helen chen over 6 years ago in reply to aida keiji

TI__Mastermind 40080 points

Dear Sir,

I'll down load ZUKEN's CR-5000 Viewer to see whether it could open it, please wait in patient.

0 Helen chen over 6 years ago in reply to Helen chen

TI__Mastermind 40080 points

Dear Sir,

the location of the output cap is really strange, why don't they put caps just across the output pin?

0 aida keiji over 6 years ago in reply to Helen chen

Prodigy 70 points

Hi Helen,

sorry.

It was designed by people of the past, and I do not know what that design intent is.

Certainly, the arrangement of the data sheet and evaluation board is not obeyed.

Is ripple the cause of fever?

Does noise or ripple occur. Is it possible to destroy the IC?

Best regards,

Keiji Aida

0 Helen chen over 6 years ago in reply to aida keiji

TI__Mastermind 40080 points

Dear Keiji,

Only one board has problem or many boards have the same problem? I guess it is caused by the poor assemebly/ or poor layout, you can resolder the parameter to check which part is wrong.

0 Helen chen over 6 years ago in reply to aida keiji

TI__Mastermind 40080 points

By the way, please solder some ceramic caps at the TPS61089's output side to check whether it could be helpful? Maybe the ground is too noise which cause the stability problem.

0 aida keiji over 6 years ago in reply to Helen chen

Prodigy 70 points

Hi Helen,

Thank you.

The same event is expected to increase by 3/600 (0.5%).

First of all, as suggested, I will try to try to put a capacitor close to the output.

Please help if you are in trouble again.

Best regards,

Keiji Aida

0 Helen chen over 6 years ago in reply to aida keiji

TI__Mastermind 40080 points

suggest you put at least 2-3 pcs 10uF ceramic cap as close to the IC as possible to check.

0 aida keiji over 6 years ago in reply to Helen chen

Prodigy 70 points

Hi Helen,

We are planning to move C15 to C18 of the circuit diagram attached above.

Best regards,
Keiji Aida

0 Helen chen over 6 years ago in reply to aida keiji

TI__Mastermind 40080 points

Good Luck!

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TPS61089: # TPS61089 SW-Pin and GND- Pin were shorted inside the IC